1. Field of the Invention
The present invention relates to a retractable lens barrel, and more particularly, to a retractable lens barrel for use in a video camera, a still camera, or other image pickup apparatuses.
2. Description of the Related Art
In recent years, downsizing and thinning of a video camera and a still camera have been strongly required. In order to realize the downsizing and the thinning, it has been common to cause photographic lenses to retract to be housed in a thin body. However, recently, in order to realize further thinning, there has been proposed a first conventional art in which, when the photographic lenses are retracted, a certain unit of the photographic lenses is retreated so as to be deviated from an optical axis.
For example, the first conventional art of a still camera having a lens unit composed of three lenses (optical elements) L1, L2 and L3 as shown in FIGS. 10A and 10B is disclosed. In the still camera, all the lenses are located on the same photographic optical axis Z1 as shown in FIG. 10A in a photographing condition, and when the lenses are retracted, the lens L2 is retreated to a position different from that on the optical axis Z1 as shown in FIG. 10B (for example, refer to Japanese Patent Application Laid-Open No. 2003-315861).
Further, a second conventional art in which a converter lens is retreated out of a photographic optical axis while rotating has also been disclosed (for example, refer to Japanese Patent Application Laid-Open No. S63-135908).
However, the still camera of the first conventional art is constructed so that an optical axis Z1′ of the lens L2 after retreat and the photographic optical axis Z1 are in parallel to each other.
Therefore, when a diameter of the lens L2 is larger than a thickness thereof, there is a problem in that a size of a lens barrel of the lens L2 in a direction perpendicular to the optical axis Z1, that is, a radial size of the lens barrel of the lens L2 is increased.
Further, in the second conventional art, a rotation axis of the converter lens does not move though is perpendicular to the photographic optical axis, and accordingly, there is a problem in that a thickness of a lens barrel thereof in a direction of the photographic optical axis is increased.